Do note it is unwise to have more than one real-time antivirus running on your computer. They can serve to disable each other’s abilities.
If you are concerned you have a latent infection, download a self-booting version of AVG or Avast and boot up with that (it boots Linux) and do an antivirus scan with Windows completely disabled. You may very well find something.
Personally, I would download a separate AV than what you currently use. I highly recommend Avira’s free emergency disk, available here:
http://www.avira.com/en/download/product/avira-rescue-system
downloading that now, thanks
they look like they have a lot of useful stuff!